The present invention relates to a surface processing method and an apparatus for carrying out the same and, more particularly, to an improved surface processing method capable of processing the surface of a solid article, such as a semiconductor work or a metal work, at a high processing speed without significantly damaging the surface of the solid work, and to an apparatus suitable for carrying out the surface processing method.
A plasma has often been used in forming a minute pattern on the surface of a semiconductor work by etching. A dry etching process disclosed, for example, in Japan. J. Appl. Phys., Vol. 12, No. 1, p.154 (1973) produces a plasma of CF.sub.4 by means of electromagnetic waves of 13.6 MHz, and etches Si or SiO.sub.2 using the plasma. This dry etching process is advantageous over the conventional wet etching process in forming a minute pattern on a semiconductor substrate, but has a problem that the semiconductor substrate is damaged by charged particles contained in the plasma.
To obviate damages attributable to the charged particles, etching processes employing electrically neutral particles are disclosed in Japanese Patent Laid-open (Kokai) Nos. Sho 61-113775 and Sho 62-259443. The etching process disclosed in Japanese Patent Laid-open (Kokai) No. Sho 61-113775 employs a molecular beam produced by thermally exciting molecules of chloride or the like by heating in a furnace for etching. The etching process disclosed in Japanese Patent Laid-open (Kokai) No. Sho 62-259443 etches a substrate by promoting the interaction between a halogen gas and the substrate by the kinetic energy of neutral particles obtained by neutralizing Ar ions or the like produced in a plasma through charge exchange. Although these prior art etching processes are able to avoid damaging the substrate by the electric charge of the charged particles, the etching rate of these prior art etching processes is in the range of a tenth to a hundredth of the conventional etching process using a plasma.